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Thread: First laser and safety - beginner corner

  1. #1
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    Laser Warning First laser and safety - beginner corner

    Hi guys, new laser Hobbyist here (total beginner in fact)

    Just to dont warn you too much, I dont plan to use it in public venue, just learning and playing a bit.

    I've read lot of posts about laser safety the past few days and i need some advice

    I've bought a laser from china (and now im sure you think "arg thats a good start ")

    I know these stuff are not very popular but ... at least i'll never be too confident to use it without safety in mind
    the thing is the unit is announced rgb 500red635 150green532 500blue450 with 40k galvos and analog modulation (isnt it great on paper )

    Sure, we will not discuss that these diodes are probably less powerfull than announced and 40k is ... to be proven
    I've not really played with it yet...(just checked it light up and answer dmx calls) because i have no ilda dac nor big place to practice ..

    Anyway i want to do something with that stuff so i think i need AT LEAST two things :

    - An ILDA DAC with a Software to manage output power (analog ouput),

    - A Concave lens with a good lens holder to reduce all that power (full concave actually or plano concave)

    I know that the DAC and reducing analog power is anything but a safety feature... but i certainly can get some buying advice about that too..
    - For the DAC im thinking of Riya lite and probably LSX, considering the price / performance

    - For the lens, i was looking for Experimental Quality Plano-Concave (PCV) Lenses on edmundoptics but didnt find a good holder yet (except the one from pangolin but i dont know if i can use it with full lens)
    ... About the lens i really want to be safe so im thinking of something like 100mm focal length concave lens (-10 diopters if im right)

    *** for sure im not planning of drawing something with that diffraction, but im sure for volumetric effect it can be good

    I was thinking about putting some filter too in front of the beam to reduce the output but didnt found anything relevant yet, so advices are welcome

    Most of conversation state that to be safe you need to have some measure about real power and diffraction, i totally got that,
    but i dont have technics or measure tool to provide accurate data, so im ready to be extra safe based on worst case (yeah but dont tell me to let the aperture closed)
    -> and i know that the more safe, the less shining it would be ...

    Ok thanks for reading my little story and if you have some suggestions i'll be happy to read you

    Moreover if you know good place to buy all that, in Canada or in US just let me know

  2. #2
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    Welcome to PL. You're still off to an ok start. And, being concerned with safety from the beginning is a good thing. I think you are on the right track and the Riya with LSX is a good way to start however, please be aware that there is a bit more of a learning curve to LSX than some other programs - Quickshow for example. However, it IS less expensive so, that's the trade off. I still open LSX up and suddenly get all stupid and give up after a few minutes. I hate the teeny tiny icons on the edges of the screen that you have to try and remember what they're for. It's just not intuitive to me. There are those left brain people like Swamidog though that can make magic with it.

    I don't know about the Edmunds lens fitting in the Pangolin mount but, I believe the specific measurements for the Pangolin mount are on their web site. It's steal for $29.95 US with the amount of machining involved. I guess you are looking to diverge the entire beam but, you still would do well just getting a Pangolin lens and keep the horizon above eye level. I think -10 dipoters is probably too much as I think Pangolin's highest is -6 diopters. You may not be happy with the output at -10.

  3. #3
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    I'll add my nickel's worth of advice, FWIW -

    As someone brand-new to lasers, stay away from "audience scanning" (even at home) until you really understand what you're doing, and you can keep your entry into the hobby much safer, and a bit less complex.

    You can do some incredible beam shows with RGB projectors that don't require scanning the beams into the audience.
    Once you remove audence scanning from the picture, you really don't need lenses and filters to attenuate your projector output ~
    in fact, for overhead beams and graphics, you're much better off without them.

    You can make a "safety mask" for your projector by taping a strip of flat-black painted aluminum foil (commercially available as "foil black") across the projector's output aperture to keep beams from accidently shooting into the area where your audience is sitting. Cheap, safe, effective, and a LOT less complicated than experienting with different lense & filter arrangements.

    Any other adjustments to output target zones, beam intensity, etc. can be made using controls within your laser software.
    Generally, you probably find that for overhead beams - even in a "home venue" environment - you'll want to use every bit of laser power your projector is capable of delivering.

    Be sure to leave room in your budget for a small fog / smoke machine ~
    You'll really need that to get the full benefit of beam shows.

    Good luck, and please post any questions you have.
    We've all been where you were at some point, and this forum is a GREAT place to get answers to any questions you might have!!

    Randy
    RR

    Metrologic HeNe 3.3mw Modulated laser, 2 Radio Shack motors, and a broken mirror.
    1979.
    Sweet.....

  4. #4
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    Thanks you both for your advices

    The thing is with a low ceilling (home ceilling), the safety space is really small, but you're right, i certainly can give it a try in the first place,

    on another side, im not really worried about losing some power or large beam, in fact im more excited with laser for ultra fast transition speed (scan speed) and rgb mixing ... at least for now

    do you guys know where i can buy dac, software, and lens, lens holder ?

  5. #5
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    Just a couple of pointers.

    1. A lens doesn't reduce the power it increases the divergence of the beam, which in turn reduces the level of irradiance at the eye (milliwatts per cm2) (not trying to sound nit picky but it's best to understand what's happening)

    2. The more diverging the lens, the more fuzzy beams appear - so its a trade off between divergence and appearance (which is where Beam Attenuation Map's (software based power reductions) help). This is the reason why Pangolin use 1/2 lens - to provide a different solution above and below the horizon that maintains the full sharpness of the beams overhead.

    3. Even using a lens, there is no magic solution. The only way to be truly safe is with an LPM and measurements and calculations as even if you diverge the beam, you can still be over the MPE limit depending on other factors. You can't just pick a lens of random strength, slap it on the front and have a guaranteed safe laser. Any diverging lens should make it safer than without a lens, but to actually know it's within safe limits, you need measurements and calculations.

    If in doubt keep it overhead.

    Regarding cheap lenses, try asking McCarrot on here as I believe he sells his own full lenses and so presumably does holders as well.

    Pangolin's lenses are very expensive because they use special optical grade multi stage lens coatings and thus whilst they are arguably the best, they are probably beyond your budget from what you were saying above.

  6. #6
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    Thanks, very interesting answer again, as you say pangolin lens are certainly the best for that , but the budget is too much for starting... (as opposite to their holder which is the cheapest i found for now)

    for the Software Beam Attenuation Map, if i understand well, this is not safe because if the software crash, i dont know exactly how the laser will react, right ?

    Some previous comment talk about safety mask, is it possible to make a safety filter, which would reduce (a lot) the output beam irradiance ?

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